There is a Malaysia Airlines ticketing office in Bangkok. Should consider stopping by at their office and getting this solved.

Address
Unit 332 B, 3rd Floor,
All Seasons Place Retail Center
87/192 Wireless Road, Lumpini,
Phathumwan, Bangkok 10330

Business Hours
Monday - Friday: 08.30 -17.30

Tel: +66 2 2506560-7

Best to solve it at their ticketing office. You are likely to get things sorted a lot faster than on the phone and in person with your documents in hand to show.